J. Labaki¹, E. Mesquita², R. K. N. D. Rajapakse³

CMES-Computer Modeling in Engineering & Sciences, Vol.103, No.5, pp. 281-313, 2014, DOI:10.3970/cmes.2014.103.281

Abstract This paper introduces a numerical model to investigate the vibratory response of elastic and rigid circular plates embedded in viscoelastic, transversely isotropic, three-dimensional layered media. In the present numerical scheme, the boundary-value problem corresponding to the case of time-harmonic concentrated and distributed axisymmetric vertical ring loads within a layered half-space is formulated according to an exact stiffness method. Its solution results in the required influence functions for the modeling of the present problem. The case of an embedded flexible plate is formulated in terms of a variational method. The deflection profile of the plate is written in terms of generalized… More >

L.Q. Liu¹, H.T. Wang^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.6, pp. 439-462, 2013, DOI:10.3970/cmes.2013.090.439

Abstract A line model-based fast boundary element method (BEM) is presented for the large-scale cathodic protection (CP) analysis of three-dimensional pipelines in layered soils. In this approach, pipelines are treated as lines with potentials assumed constant over the cross-section and the boundary integrals happen on the associated cylindrical surfaces. The advantage of this model is that pipelines can be meshed with line elements while the boundary integrals are based on the original shapes. Therefore, the number of unknowns is significantly reduced with accuracy effectively retained. A unified formulation of the multipole moments is developed for the mixed boundary element types in… More >

Frederic L. Pellet¹

CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.3, pp. 279-296, 2009, DOI:10.3970/cmes.2009.052.279

Abstract In this study, the contact and interaction between a tunnel lining support and a damage-susceptible viscoplastic medium is investigated. First, back-analysis of the time-dependent behaviour of a drift excavated across a carboniferous rock mass which exhibited large delayed displacements was undertaken. Drift closure was simulated using an elasto-viscoplastic constitutive model that included the strength degradation process. This 3D numerical simulation was performed taking into account both stage construction sequence and rate of excavation advancement. A comparison of the numerical results with the data measured on site allowed for the calibration of the model parameters. Subsequently, the installation of a concrete… More >

A. Ferrari¹, L. Laloui^1,2, Ch. Bonnard^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.3, pp. 217-236, 2009, DOI:10.3970/cmes.2009.052.217

Abstract A coupled hydro-mechanical formulation is presented for the analysis of landslide motion during crisis episodes. The mathematical formulation is used to model a natural slope affected by a multiple slip surface failure mechanism, in which pore water pressure evolution was identified as the main cause for movement accelerations. An elasto-plastic constitutive model is adopted for the behaviour of slip surfaces. Material parameters are obtained by combining the available laboratory tests and the back analysis of some crisis episodes. After being calibrated and validated, the model is applied to improve the understanding of the physical processes involved and to predict the… More >

Sarang Seyrafian¹, Behrouz Gatmiri², Asadollah Noorzad³

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.2, pp. 115-126, 2006, DOI:10.3970/cmes.2006.015.115

Abstract An analytical solution is presented for the response of a non-homogeneous saturated poroelastic half-space under the action of a time-harmonic vertical point load on its surface. The shear modulus is assumed to increase continuously with depth and also the media is considered to obey Biot's poroelastic theory. The system of governing partial differential equations, based on the mentioned assumptions, is converted to ordinary differential equations' system by means of Hankel integral transforms. Then the system of equations is solved by use of generalized power series(Frobenius method) and the expressions for displacements in the interior of the media or in the… More >

Biao Zhou^1,2,3, Xiong yao Xie^1,2, Yeong Bin Yang⁴, Jing Cai Jiang³

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.4, pp. 321-348, 2012, DOI:10.3970/cmes.2012.086.321

Abstract The vibration-based SHM (Structure Health Monitoring) system has been successfully used in bridge and other surface civil infrastructure. However, its application in operation tunnels remains a big challenge. The reasons are discussed in this paper by comparing the vibration characteristics of the free tunnel structure and tunnel-soil coupled system. It is revealed that all the correlation characteristics of the free tunnel FRFs (Frequency Response Function spectrum) will vanish and be replaced by a coupled resonance frequency when the tunnel is surrounded by soil. The above statement is validated by field measurements. Moreover, the origin of this phenomenon is investigated by… More >

P. Maghoul¹, B. Gatmiri^1,2, D. Duhamel¹

CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.1, pp. 51-76, 2011, DOI:10.3970/cmes.2011.078.051

Abstract This paper aims at obtaining boundary integral formulations as well as three dimensional(3D) fundamental solutions for unsaturated soils under dynamic loadings for the first time. The boundary integral equations are derived via the use of the weighted residuals method in a way that permits an easy discretization and implementation in a Boundary Element code. Also, the associated 3D fundamental solutions for such deformable porous medium are derived in Laplace transform domain using the method of Hérmander. The derived results are verified analytically by comparison with the previously introduced corresponding fundamental solutions in elastodynamic limiting case. These solutions can be used,… More >

Gongsheng Li¹, De Yao², Hengyi Jiang³, Xianzheng Jia¹

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.2, pp. 83-108, 2011, DOI:10.3970/cmes.2011.074.083

Abstract This paper deals with an inverse problem of determining a time-depen -dent reaction coefficient arising from a disturbed soil-column infiltrating experiment based on measured breakthrough data. A purpose of doing such experiment is to simulate and study transport behaviors of contaminants when they vertically penetrating through the soils. Data compatibility of the inverse problem is discussed showing a sufficient condition to the solution's monotonicity and positivity with the help of an adjoint problem. Furthermore, an optimal perturbation regularization algorithm is applied to solve the inverse problem, and two typical numerical examples are presented to support the inversion algorithm. Finally, transport… More >

Delfim Soares Jr.¹

CMES-Computer Modeling in Engineering & Sciences, Vol.61, No.2, pp. 177-200, 2010, DOI:10.3970/cmes.2010.061.177

Abstract In this work, meshless methods based on the local Petrov-Galerkin approach are employed for the time-domain dynamic analysis of porous media. For the spatial discretization of the pore-dynamic model, MLPG formulations adopting Gaussian weight functions as test functions are considered, as well as the moving least square method is used to approximate the incognita fields. For time discretization, the generalized Newmark method is adopted. The present work is based on the u-p formulation and the incognita fields of the coupled analysis in focus are the solid skeleton displacements and the interstitial fluid pore pressures. Independent spatial discretization is considered for… More >

D. Manzanal^1,2, M. Pastor^2,3, J.A. Fern,ez Merodo⁴, P. Mira^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.3, pp. 293-318, 2010, DOI:10.3970/cmes.2010.055.293

Abstract This paper presents an extension of the Generalized Plasticity model proposed by Pastor - Zienkiewicz in 1986. The extension is based on (i) incorporating a state dependant parameter to model the mechanical behaviour of sand under a wide range of relative densities and confining pressures (ii) the definition of the effective stress of Schrefler (1984) modified to obtain unique CSL for different suction and (iii) the work conjugated variable proposed by Houlsby (1997). Several examples are presented for saturated and unsaturated soils. More >